ISO 24527:2020 Service activities relating to drinking water supply, wastewater and stormwater systems — Guidelines on alternative drinking water service provision during a crisis.
4 Principles for alternative drinking water service provision
4.1 General
In order to determine its ADWS provision, a drinking water utility should first have a clear understanding of its normal operation during typical (non-crisis) circumstances.
During a crisis involving an interruption to drinking water distribution, the drinking water utility should ensure an ADWS is provided to users and also ensure that assets which are intended to be used in contact with drinking water are authorized by the relevant authority. Such assets could include cleaned and disinfected drinking water containers.
Ideally, users should only take containerized drinking water according to predetermined drinking water allocation(s), see Annex C. However, in practice, with high user demand and limited drinking water utility resources available to control the issuing of drinking water, this can be difficult to achieve.
The drinking water utility’s pre-planning of issuing drinking water should aim to ensure a suitable level of control, including a contingency for excessive withdrawals. Inability to exercise such control can lead to legitimate users’ needs remaining unfulfilled. This can have consequences, including a decline in ADWS service levels and financial and reputational impacts. Drinking water utilities can encourage users to exercise restraint by providing adequate public information both in advance of and during a crisis (see Clause 7).
The required water quality for ADWS provision is determined by the relevant authorities and/or responsible bodies. However, the possible need to distribute non-drinking water through the drinking water distribution network (if necessary, and in parallel with ADWS) should also he recognized. Such a measure can he necessary for public health (e.g. toilet flushing) and public safety (e.g. firefighting) reasons. In such circumstances, the water usage constraints that need to be complied with should be Strongly emphasized through stakeholder communications.
4.2 Alternative drinking water service approaches
4.2.1 General
The drinking water utility can adopt one or both of the ADWS approaches described in 422 and 42.
4.2.2 Using the drinking water distribution network in a non-conventional manner
This approach involves the drinking water utility supplying drinking water to users via the drinking water distribution network but using different means than the regular operational methods.
Proven methods of ADWS provision using the distribution network in a non-conventional manner are described in 2.
4.2.3 Not using the drinking water distribution network
This approach involves temporary points of distribution (TPDs) being established throughout the affected service area. Examples of TPD methods are described in Annex A. The drinking water utility should, during its normal operations (i.e. prior to the onset of a crisis), have communicated to users the need to approach a TPD to receive drinking water during a crisis. This approach allows the drinking water utility to provide users with drinking water reasonably close to their normal point of use. ISO 24527 pdf download.